1. Field of the Invention
The present invention relates to a vacuum cleaner, and in particular, to a multi-cyclone dust collection apparatus, which is employed in a vacuum cleaner so as to filter dirt suctioned from a surface to be cleaned together with air, using centrifugal force over two or more steps.
2. Description of the Related Art
In general, a cyclone vacuum cleaner comprises a bottom brush for suctioning dirt from a surface to be cleaned together with air, a motor driving chamber provided with a driving source, and a vacuum cleaner body provided with a cyclone collection apparatus.
The cyclone collection apparatus is constructed in such a way that dust-entrained air, which is introduced from the bottom brush, is caused to form a swirling air stream so that dirt is separated from the air by centrifugal force, the dirt is collected, and clean air is discharged into the motor driving chamber. In recent years, in order to improve the dust collection efficiency, there has been proposed a multi-cyclone dust collection apparatus that separates dust entrained in air over two or more steps, wherein such a multi-cyclone dust collection apparatus comprises one or more secondary cyclones.
The above-mentioned types of conventional multi-cyclone dust collection apparatuses are disclosed in WO02/067755 and WO02/067756 (by Dyson Ltd.). However, such conventional multi-clone dust collection apparatuses are mainly applied to an upright type cleaner but hard to be applied to a canister-type cleaner because an upstream cyclone (a first cyclone) and a downstream cyclone (a second cyclone) are vertically arranged, thereby increasing the entire height of the dust-collection apparatus.
In order to solve the above problems, Korean Patent Application No. 2003-62520 discloses a multi-cyclone dust collection apparatus in which second cyclones are arranged around a first cyclone. However, efforts for reducing heights of dust collection apparatus have been continued so as to miniaturize cleaners. In addition, such a dust collection apparatus is configured in such a manner that ambient air is introduced into an upper part of the first cyclone and discharged through upper parts of the second cyclones. Thus, even in an upright type cleaner, an airflow path from the bottom brush of the cleaner to the air inlet of the first cyclone of the cyclone dust collection apparatus, and an airflow path from the air outlet of the second cyclone to the motor driving chamber provided at the bottom part of the cleaner are too long. As a result, there is a problem in that the loss in suction force in the piping of the cleaner is too high.